Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
  • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
  • H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type

Definitions

• the invention is related to the field of resonant wireless power (RWP), and in particular to an open-circuit impedance control of a RWP receiver for voltage limiting.
• RWP resonant wireless power
• a resonant wireless power receiver includes a matching network designed to resonate at the frequency of power transfer. This feeds into a semiconductor rectifier, then a dc/dc converter in order to convert the AC power to regulated DC. If the magnitude of the AC voltage exceeds the operating voltage of the rectifier, or if the rectified voltage exceeds the operating voltage of the dc/dc converter, these circuits can be damaged.
• a resonant wireless power (RWP) receiver includes an inductor element that couples with a resonant wireless power source.
• a capacitor arrangement is coupled to the inductor element altering the open-circuit impedance of the RWP receiver to reduce the ac voltage under certain defined situations.
• the capacitor arrangement includes a plurality capacitors tuned to a control ac voltage in the RWP receiver.
• a resonant wireless power (RWP) system includes a source circuit having a reflected impedance in series with a source coil.
• a receiver circuit is coupled to the source circuit using an inductor element, and includes a capacitor arrangement coupled to the inductor element altering the open-circuit impedance of the receiver circuit to reduce the ac voltage under certain defined situations.
• the capacitor arrangement includes a plurality capacitors tuned to a control ac voltage in the receiver circuit.
• FIG. 1 is a schematic diagram illustrating a resonant wireless power (RWP) system used in accordance with the invention
• FIG. 2 is a circuit diagram illustrating a series-parallel receiver circuit with Zoc adjustment capacitor
• FIG. 3 is a circuit diagram illustrating a parallel-series receiver circuit with Zoc- adjustment capacitor
• FIG. 4 is a circuit diagram illustrating a RWP receiver with a diode rectifier
• FIG. 5 is a circuit diagram illustrating a series-parallel receiver with modulation capacitors switched to ground.
• the invention provides novel techniques for adaptively altering the open-circuit impedance of the resonant receiver to reduce the ac voltage under certain defined situations.
• FIG. 1 shows a resonant wireless power (RWP) system.
• RWP resonant wireless power
• Mutual inductance, or coupling, between the source coil LI and receiver coil L2 can be modeled in a number of different ways.
• the coupling k is modeled as a current-controlled voltage source Voc in series with the receiver coil L2.
• the impedance seen by this voltage source Voc which includes the coil L2, matching network 6 and load (e.g., rectifier, dc/dc, load current) Rl, is Zoc.
• the effect of the coupling is an impedance in series with the source coil LI called Zref, the reflected impedance.
• Both the open-circuit impedance and the reflected impedance are complex quantities— they have real (resistive) and imaginary (reactive) components.
• the reflected impedance is related to the open-circuit impedance by this formula:
• the capacitor Cd can be switched in or out of the circuit.
• the open-circuit impedance is altered as a result. If the switch is open, the open-circuit impedance Zoc is given by If the switch is closed, Zoc is given by
• a capacitor that can be switched in to adjust the open-circuit impedance Zoc, such as Cd in this example, is defined as a Zoc-adjustment capacitor.
• the two open-circuit impedances can be represented as the "X" and "O" symbols on the complex impedance plane 10, as shown in FIG. 2.
• the magnitude of the change depends on the relative values of the inductors L2 and capacitor s C2a, C2b, Cd in the resonant circuit 8.
• Changing the open-circuit impedance also changes the reflected impedance seen by the source. Depending on the tuning of the system, either one may give a higher ac voltage at the rectifier input.
• a RWP receiver in one of two ways:
• the circuit of FIG. 2 has the particular advantage that the voltage across the switch 9 is reduced compared to the coil voltage. This is advantageous for the implementation of the switch in a
• FIG. 3 shows a parallel-series topology of a receiver circuit 12 that includes a Zoc-adjustment capacitor.
• the Zoc-adjustment capacitor Cd can be either normally in-circuit or normally out-of-circuit.
• the circuit 12 of FIG. 3 also has the advantageous property that the voltage across the switch 13 can be substantially lower than the coil voltage, provided that C2b is not much larger than C2a.
• FIG. 4 shows an implementation of a receiver circuit 14 in which the ac power is rectified using a diode rectifier 16 to produce a dc voltage supply VRECT.
• This circuit can be represented for AC analysis by the circuit of FIG. 2. Any design of a rectifier can be used, including a synchronous rectifier. Note the modulation capacitor Cm is similar to the capacitor Cd, as shown in FIG. 2.
• FIG. 5 shows an alternative implementation of the modulation circuit 18 that is electrically equivalent to FIG. 4.
• the modulation capacitance is split into two capacitors of value 2Cm.
• the series combination of these two capacitors has a capacitance Cm.
• the techniques described herein adaptively alters the open-circuit impedance of any resonant receiver to reduce the ac voltage.
• the invention allows one to change the open-circuit impedance that also changes the reflected impedance seen by a source by tuning the system to produce a higher ac voltage at a rectifier input.
• the invention demonstrate several designs of a RWP receiver by tuning the receiver for normal operation with the switch open, and close the switch in an excess power condition to reduce the ac voltage at the rectifier input.
• a receiver can be tuned for normal operation with the switch closed, and open the switch in an excess power condition to reduce the ac voltage at the rectifier input.

Landscapes

• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Power Engineering (AREA)
• Rectifiers (AREA)
• Circuits Of Receivers In General (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=50389137

Family Applications (1)

Country Status (3)

Cited By (3)

Families Citing this family (9)

Family Cites Families (11)

• 2013
  • 2013-09-27 WO PCT/US2013/062066 patent/WO2014052686A2/fr not_active Ceased
  • 2013-09-27 CN CN201711363468.7A patent/CN107968490A/zh not_active Withdrawn
  • 2013-09-27 CN CN201380051118.0A patent/CN105074848B/zh active Active
  • 2013-09-27 US US14/355,212 patent/US10014724B2/en active Active

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